Method of producing galvanized corrugated metal pipe



April 5,1927. 1,623,618

J. COOK 1 METHOD OF PRODUCING GALVAN EEEEEEEEEEEEEEEEEEEEE PE PatentedApr. '5, 1927.

UNITED STATES PATENT OFFICE.

i J. COOK, OF YVHEELING, WEST VIRGINIA, ASSIGNOR T WHEETJING STEEL GOBPORATION," OF WHEELING, WEST VIRGlNIA, .A CORPORATION OF DELAWARE.

METHOD OF PRODUCING GALVANIZED CORRUGATED METAL PIPE.

Application filed May 5, 1924. Serial 1 10. 711,287.-

This invention relates to processes of manufacturing galvanizedcorrugated sheet metal pipe, and it has for its primary object toprovide a process or method of producing 5 galvanized corrugated steelor iron culvert pipe which shall possess greatly superior resistance torust and corrosion over pipe made by preexisting methods, and -which,consequently, shall have much longer life than that of pipe made by themethods in general use. x

, The method heretofore universally followed in the production ofgalvanized cor rugat'ed pipe has been, first, to pickle the sheet in itsflat form, then to galvanize the sheet in the flat, then to corrugatethe sheet, then to bend the galvanized corrugated sheet into pipe form,and, finally, to rivetthe overlapping edges.

Figure 2is an end elevation of the corrugated sheet as it appears afterit has been curved into tubular form preparatory to galvanizing Figure 31s a side elevation of the pipe following galvanizing and riveting; and

Figure 4 is an end View of the same.

The invention consists in the performance of certain essential steps inthe production of galvanized corrugated sheet metal pipe in thefollowing order: I v

First: pi kling the metal sheet in the flat;

Second: corrugating the sheet;

Third :shearing the sheet to size;

Fourth: curvin the corrugated sheet into approximately tu ular'form;

liifth: galvanizing the tubular sheet; an

Sixth: closingthe edges of the sheet upon a each other and riveting themtogether.

In the curving operation, the corrugated sheet shown. in Fig. '1 is bentinto approximate] the form shown in Fig. 2, in which the e ge portionsto be overlapped and riv- The present method difiers from that hereetedlie but of contact with each other, or

are separated to such extent that, when the edge portions. 01', if saidedge portions directly be made to come in contact with each other, theymay be suitably wedged apart preliminary to introduction of the tube inthe galvanizing bath. The life of galvanize'd corrugated pipe is verylargely dependeiit upon the thickness and density of the coating-metalcarried by the pipethat is, upon the quantity of coating borne per unitTof area.

Employing galvanized steel and iron sheets carryingin excess of 1.75ounces of coating material to each square foot of surface area, it is aphysical impossibility to corrugate the sheets and bend them intotubular form in the usual culvert diameters I without resultantcracking, or fracture, and

peeling of the coating. And, due to this fact, pipe carrying a coatingof two ounces per square foot of surface area, which is the minimumcoating called for by governmental specifications for galvanized andcorrugated culvert pipes, is necessarily defective, numerous cracks andpeels being produced as a result of the deflection in the formingprocess. The coating on the inner surfaces of the bends produced informing the pipe, be-

- ing subject to compression, becomes buckled,

while that on the outer surfaces of said bends develops numerousdistinct cracks, or fractures, due to the tension placed on the coating. Thus, to obviate the objections noted, the application of thecoating in the galvanizing process is made to fol-low 'the steps ofcorrugating the sheet and shaping thereof into substantially tubularform, as hereinbefore stated. So coated, it is entirely prac ticable toapply three or more ounces. of

coating to the square foot with absolute assurance that the coating willnot show cracks or-peels in the finished product. In other words, sincethe product is not subjected to severe bending strains followinggalvanizing, it may have a very heavy coating of galvanizing material,and such coating will possess great density and be free from fracturesor other imperfections developed in the manufacture of the pipe.Additionally,

due to the application of the coating subsequent toshearin to size, theedges, as well as the faces, of t e sheets are coated.

What is claimed is 1. The method of making galvanized corrugated sheetmetal pipe, which consists in galvanizing the metal subsequent to thesteps of corrugating the sheet and curving the same into tubular formand prior to closing the overlapping ed es upon each other.

2. Themethod 0% making galvanized corrugated sheetmetal pipe, whichconsists in corrugating the sheet in the flat, then curving the sheetinto approximately tubular rugated sheet metal pipe, which consists incorrugating the sheet in the flat, then curving the sheet into anapproximately tubular form wherein the meeting edges lie out of contactwith each other, then dipping the pre curved sheet'in the galvanizingbath, and finally riveting said meeting edges.

4. The. method of making galvanized corrugated sheet metal pipe, whichconsists in corrugating the sheet in the flat, then curving the sheetinto an approximately tubular form whei-einthe edges to be attachedtogether are slightly separated, then dipping the pre-curved sheet inthe galvanizing bath, and finally attaching said edges one to the other,

In testimony whereof, I aflix my signature.

\VILLIAM J. COOK.

